A technique commonly used to open plugged coronary arteries has been successful in clearing blocked fallopian tubes, a leading cause of female infertility, researchers said on Tuesday.

Under the procedure, called transcervical balloon tuboplasty, a thin flexible tube with a deflated balloon at the tip is inserted through the vagina and into the uterus, from where it is guided into a fallopian tube.

Once inside, the balloon is repeatedly inflated to open a passageway through the obstruction. The same technique is used to open coronary arteries blocked by fatty deposits.

Out of 77 women treated with tuboplasty at six medical centers around the country, 92 percent had at least one fallopian tube opened and 69 percent had both tubes unblocked, said Dr. Edmond Confino of Mount Sinai Hospital Medical Center and Rush Medical College.

Of 64 women who were followed for an average of one year after the procedure, 34 percent became pregnant, he said. Seventeen women had normal deliveries and five miscarried, he said. One woman had an ectopic pregnancy, meaning one that occurs outside the uterus.

``This is exactly the type of pregnancy outcomes we would expect in our special patient population of older women who have had longstanding infertility problems,`` said Dr. Norbert Gleicher, a member of the study team and director of the Center for Human Reproduction. The study appears in today`s Journal of the American Medical Association.

The average age of the women in the study was 33, and most had been unable to conceive for more than a year.